Publications by authors named "Dwight Bowman"

133 Publications

Effectiveness of Credelio Plus, a novel chewable tablet containing milbemycin oxime and lotilaner for the treatment of larval and immature adult stages of Toxocara canis in experimentally infected dogs.

Parasit Vectors 2021 May 17;14(1):256. Epub 2021 May 17.

Daniel E. Snyder, DVM PhD. Consulting, LLC, Indianapolis, IN, 46229, USA.

Background: The ascarid, Toxocara canis, is a common and important zoonotic intestinal nematode parasite that infects dogs globally. An effective treatment that kills any pre-patent stages of immature T. canis could additionally reduce or eliminate the development of patent infections that can result in clinical disease in infected dogs and would further reduce environmental contamination of eggs. Two randomized, blinded, GCP-compliant, pivotal laboratory dose confirmation studies were conducted to assess the effectiveness and safety of a new novel combination of lotilaner and milbemycin oxime tablets (Credelio Plus) administered orally to dogs that were experimentally infected with immature (L4 or immature adult [L5]) stages of T. canis.

Methods: The commercial tablet formulation of Credelio Plus was administered in a time frame relative to inoculation with infective eggs. This allowed for effectiveness to be assessed against each specific immature stage of T. canis. In each study, dogs were randomized and allocated to one of four treatment groups. Each treatment group contained ten dogs that had been experimentally inoculated on Day 0 with infective T. canis eggs and then were dosed once on Day 14 or Day 24 using either placebo tablets or Credelio Plus tablets (IP) to provide minimum dosages of 0.75 mg/kg of milbemycin oxime and 20 mg/kg of lotilaner. All dogs were necropsied 5 or 6 days after their respective treatment. At necropsy, all nematodes recovered from the gastrointestinal tract were counted by species and stage.

Results: In both dose confirmation studies using geometric mean worm counts, effectiveness of Credelio Plus was ≥ 98.6% and ≥ 96.8% against L4 larval stage T. canis and immature adult [L5] T. canis in both studies, respectively.

Conclusions: These studies demonstrated that the Credelio Plus combination tablet administered orally to dogs was highly efficacious against experimental infections with L4 and immature adult [L5] stages of T. canis.
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http://dx.doi.org/10.1186/s13071-021-04762-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8127296PMC
May 2021

Effectiveness of a novel orally administered combination drug product containing milbemycin oxime and lotilaner (Credelio Plus) for the treatment of larval and immature adult stages of Ancylostoma caninum in experimentally infected dogs.

Parasit Vectors 2021 May 17;14(1):255. Epub 2021 May 17.

East Tennessee Clinical Research Inc., Rockwood, TN, USA.

Background: The hookworm, Ancylostoma caninum, is a common and important zoonotic intestinal nematode parasite that infects dogs globally. Both the immature and adult stages of A. caninum ingest large volumes of blood during the feeding process and can cause severe anemia and death in young dogs, even before patent infections can be diagnosed using routine faecal examination methods. Thus, effective treatment of any pre-patent stages of immature hookworms can reduce or eliminate the risk of clinical disease in infected dogs and additionally reduce environmental contamination of eggs and infective larvae. Two randomized, blinded, GCP-compliant, pivotal laboratory dose confirmation studies were conducted to evaluate the effectiveness and safety of a new novel combination of lotilaner and milbemycin oxime tablets (Credelio Plus) administered orally to dogs experimentally infected with immature (L4 and immature adult [L5]) stages of A. caninum.

Methods: Treatments using the intended global commercial tablet formulation of Credelio Plus were administered in a time frame relative to inoculation with infective larvae so that effectiveness could be assessed against each specific immature stage of A. caninum. In each study, dogs were randomized to one of six (study 1) or four (study 2) treatment groups. Each treatment group contained 8 (study 1) or 10 (study 2) dogs that had been experimentally inoculated with infective A. caninum larvae on day 0 and were dosed once on day 7 or day 11. Enrolled subjects were administered placebo tablets, Credelio Plus tablets, or lotilaner mono tablets to provide minimum dosages of 0.75 mg/kg of milbemycin oxime and 20 mg/kg of lotilaner. All dogs were necropsied 5 days after their respective treatment. All nematodes recovered from the gastrointestinal tract at necropsy were counted by species and stage.

Results: For both dose confirmation studies and based on geometric mean worm counts, efficacy of Credelio Plus was ≥ 97.3% against L4 larval stage of A. caninum and ≥ 98.7% against immature adult (L5) A. caninum.

Conclusions: These studies demonstrated that the orally administered Credelio Plus combination tablet was highly efficacious in treating immature (L4 and immature adult [L5]) stages of A. caninum in experimentally infected dogs.
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http://dx.doi.org/10.1186/s13071-021-04761-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8127199PMC
May 2021

Feline ophthalmomyiasis externa caused by larvae: four cases (2005-2020).

J Feline Med Surg 2021 May 14:1098612X211013021. Epub 2021 May 14.

Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.

Case Series Summary: Described are four cats diagnosed with ophthalmomyiasis externa caused by larvae. Medical records were retrospectively reviewed to identify cats with ophthalmomyiasis externa between 2005 and 2020 at Cornell University Hospital for Animals. Signalment, history, clinical and diagnostic findings, treatment and outcome were recorded. All cats were young (< 3 years of age), had outdoor access and were initially examined during the summer months. All cases had unilateral disease with the right eye affected. Two cases had nictitating membrane lesions and two had orbital disease. Concurrent superficial corneal ulceration was present in three cats. Two cats suffered from pyrexia, suspected secondary to inflammation from the larval infestation. Successful larval removal was performed in all cats, which resulted in improvement of discomfort and clinical signs. A corneal ulcer persisted in one cat, which was lost to follow-up prior to ulcer resolution. Parasite identification confirmed species infestation in all cases.

Relevance And Novel Information: To the authors' knowledge, this is the first report of feline ophthalmomyiasis externa caused by species. Parasite removal was successful in restoring comfort and resolving clinical signs in all cats with adequate follow-up information.
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http://dx.doi.org/10.1177/1098612X211013021DOI Listing
May 2021

SENTINEL COYOTE PATHOGEN SURVEY TO ASSESS DECLINING BLACK-FOOTED FERRET (MUSTELA NIGRIPES) POPULATION IN SOUTH DAKOTA, USA.

J Wildl Dis 2021 04;57(2):264-272

US Geological Survey, National Wildlife Health Center, 6006 Schroeder Rd., Madison, Wisconsin 53711, USA.

As part of the national recovery effort, endangered black-footed ferrets (Mustela nigripes) were reintroduced to the Cheyenne River Sioux Reservation in South Dakota, US in 2000. Despite an encouraging start, numbers of ferrets at the site have declined. In an effort to determine possible causes of the population decline, we undertook a pathogen survey in 2012 to detect exposure to West Nile virus (WNV), canine distemper virus (CDV), plague (Yersinia pestis), tularemia (Francisella tularensis), and heartworm (Dirofilaria immitis) using coyotes (Canis latrans) as a sentinel animal. The highest seroprevalence was for WNV with 71% (20/28) of coyotes testing antibody-positive. Seroprevalence of CDV and plague were lower, 27% and 13%, respectively. No evidence of active infection with tularemia or heartworm was seen in the coyotes sampled. As this study did not sample black-footed ferrets themselves, the definitive cause for the decline of this population cannot be determined. However, the presence of coyotes seropositive for two diseases, plague and CDV, lethal to black-footed ferrets, indicated the potential for exposure and infection. The high seroprevalence of WNV in the coyotes indicated a wide exposure to the virus; therefore, exposure of black-footed ferrets to the virus is also likely. Due to the ability of WNV to cause fatal disease in other species, studies may be useful to elucidate the impact that WNV could have on the success of reintroduced black-footed ferrets as well as factors influencing the spread and incidence of the disease in a prairie ecosystem.
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http://dx.doi.org/10.7589/JWD-D-20-00015DOI Listing
April 2021

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel for the prevention of heartworm disease in cats.

Parasite 2021 2;28:30. Epub 2021 Apr 2.

College of Veterinary Medicine, Cornell University, Ithaca, 14850 NY, USA.

NexGard Combo is a novel topical endectoparasiticide formulation for cats combining the insecticide/acaricide esafoxolaner, the nematodicide eprinomectin and the cestodicide praziquantel. The efficacy of this novel formulation for the prevention of heartworm disease in cats was tested in two experimental studies using an induced infection model and a randomized, blinded, placebo-controlled study design, and two USA isolates of Dirofilaria immitis. In each study, 20 naïve cats were each inoculated sub-cutaneously with 100 third-stage larvae of D. immitis 30 days before treatment. Following randomization to two treatment groups of ten cats, each cat was treated topically once, either with the minimum recommended dose of the novel formulation, or with an identical volume of placebo. Five months after treatment (6 months after infections), the cats were humanely euthanized for parasite recovery and count. Efficacy was calculated by comparison of the numbers of adult D. immitis recovered in the control and in the novel formulation groups. In the control groups of each study, D. immitis were recovered in seven and nine cats (respective worm counts ranges 1-7 and 1-16, respective geometric means 1.6 and 5.1). In both studies, none of the treated cats harbored any D. immitis at necropsy and the calculated efficacy of the novel formulation was 100%. There were no adverse reactions related to treatment with the novel formulation. The results of these two studies demonstrate that a topical NexGard Combo application at the minimum label dose is well-tolerated and efficacious in preventing heartworm disease in cats.
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http://dx.doi.org/10.1051/parasite/2021026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8019556PMC
April 2021

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel against Echinococcus multilocularis infections in cats.

Parasite 2021 2;28:29. Epub 2021 Apr 2.

Boehringer-Ingelheim Animal Health, 29 Avenue Tony Garnier, 69007 Lyon, France.

NexGard Combo, a novel topical endectoparasiticide formulation for cats combining esafoxolaner, eprinomectin and praziquantel, for the treatment of internal and external parasite infestations, including arthropods, nematodes and cestodes, was tested for efficacy against induced infections of Echinococcus multilocularis in cats, in two experimental studies. The two studies were performed in the United States with the same E. multilocularis isolate sourced locally. In each study, 20 cats were inoculated intra-gastrically with ~30,000 E. multilocularis protoscoleces three weeks before treatment, then ten cats were randomly allocated to a placebo control group or to the novel formulation treated group. Inoculated cats were treated topically once at the minimum recommended dose of the novel formulation, or with an identical volume of placebo. One week after treatment, cats were humanely euthanized for parasite recovery and count. The efficacy calculation was based on comparison of number of scoleces found in the control group and the novel formulation group. In the two control groups, E. multilocularis scoleces were found in five (range: 30-1025) and eight (range 2-345) cats, the geometric means inclusive of the ten cats per group were 8.9 and 28.8, respectively. In the two novel formulation-treated groups, none of the cats harbored any E. multilocularis scoleces, demonstrating 100% efficacy.
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http://dx.doi.org/10.1051/parasite/2021025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8019559PMC
April 2021

Ascaris and Toxocara as foodborne and waterborne pathogens.

Authors:
Dwight D Bowman

Res Vet Sci 2021 Mar 28;135:1-7. Epub 2020 Dec 28.

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, United States of America. Electronic address:

This is a review on the current status of Ascaris and Toxocara as agents of disease as a foodborne pathogen that is often transmitted onto produce via contaminated water. The paper introduces the parasites, their biology, disease caused, and mode of transmission. It summarizes recent research on methods for the detection of the parasites on crops, their prevalence in recent surveys of ready to eat plants in different parts of the world, and potential aspects of their means for remediation on vegetable crops. Also discussed is the ubiquitous nature of the presence of these eggs in the environment due to the many humans infected and means currently underway to control these parasites though improve water quality, sanitation, and hygiene.
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http://dx.doi.org/10.1016/j.rvsc.2020.12.017DOI Listing
March 2021

Selected advanced imaging techniques were unable to quantify in vivo parasitic burden in heartworm-infested dogs.

Vet Radiol Ultrasound 2021 Jul 22;62(4):471-475. Epub 2020 Dec 22.

College of Veterinary Medicine, Department of Clinical Sciences, Cornell University, Ithaca, New York.

This prospective exploratory study aimed to determine whether certain noninvasive advanced imaging techniques could estimate parasitic burden in heartworm-infested dogs; a noninvasive method is needed for ethical considerations and permitting longitudinal drug studies. Three cardiac-gated and respiratory-gated 3T MRI techniques and CT pulmonary angiography (CTPA) were performed in three healthy beagles to optimize imaging techniques. Once the imaging techniques were established, a pilot study was performed to determine which one of the MRI techniques would be used in an observer comparison study. Ultimately, spoiled gradient recalled (SPGR)-cine-MRI and CTPA were performed in four and five heartworm-infested dogs, respectively. Heartworms were detected in the pulmonary arteries in all dogs during SPGR-cine-MRI and in no dog during CTPA. However, counting the number of worms was unsuccessful. In conclusion, CTPA and SPGR-cine-MRI were unable to replace necropsy for quantifying parasitic burden in heartworm-infested dogs.
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http://dx.doi.org/10.1111/vru.12945DOI Listing
July 2021

sclerokeratitis in a cat.

J Am Vet Med Assoc 2020 Dec;257(12):1280-1287

Case Description: A 12-year-old neutered male domestic shorthair cat with chronic anterior uveitis and secondary glaucoma of the right eye was examined for persistent blepharospasm 2 weeks after corneal debridement and grid keratotomy for nonhealing superficial ulcerative keratitis.

Clinical Findings: Examination of the right eye revealed a central superficial corneal ulcer associated with corneal epithelial and subepithelial infiltrates and mild aqueous flare. Structures consistent with amoeboid cysts and trophozoites were detected in the cornea by in vivo confocal microscopy. Suppurative keratitis was identified cytologically. An spp was isolated through culture and identified by a PCR assay of corneal specimens.

Treatment And Outcome: Symptomatic and antiamoebic (polyhexamethylene biguanide 0.02% ophthalmic solution) treatments were instituted. Over the following 6 weeks, the cat lost vision in the affected eye and lesions progressed to nonulcerative stromal keratitis associated with a dense paracentral corneal stroma ring infiltrate and anterior lens luxation. The globe was enucleated, and lymphoplasmacytic sclerokeratitis, anterior uveitis, and retinal detachment were noted. organisms were detected within the corneal stroma and anterior sclera with histologic and immunohistochemical stains. The amoebae were classified to the T4 genotype by DNA sequencing. The cat had no medical problems attributed to infection over 36 months after enucleation, until the cat was lost to follow-up.

Clinical Relevance: Naturally acquired sclerokeratitis is described in a cat for the first time. infection should be considered for cats with superficial corneal disease refractory to appropriate treatments and especially occurring after ocular trauma, including keratotomy.
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http://dx.doi.org/10.2460/javma.257.12.1280DOI Listing
December 2020

Parasites and vector-borne diseases disseminated by rehomed dogs.

Parasit Vectors 2020 Nov 10;13(1):546. Epub 2020 Nov 10.

Institute of Animal Hygiene and Veterinary Public Health, University of Leipzig, Leipzig, Germany.

The Companion Vector-Borne Diseases (CVBD) World Forum is a working group of leading international experts who meet annually to evaluate current scientific findings and future trends concerning the distribution, pathogenesis, clinical presentation, diagnosis and prevention of vector-borne infections of dogs and cats. At the 14th Symposium of the CVBD World Forum in Trieste, Italy (March 25-28, 2019), we identified the need to (i) bring attention to the potential spread of parasites and vectors with relocated dogs, and (ii) provide advice to the veterinary profession regarding the importance of surveillance and treatment for parasites and vector-borne infections when rehoming dogs. This letter shares a consensus statement from the CVBD World Forum as well as a summary of the problem faced, including the role of veterinary professionals in parasite surveillance, causal issues, and the importance of interdisciplinary cooperation in addressing the problem. To limit opportunities for dissemination of parasites and vectors, whenever possible, underlying problems creating the need for dog rehoming should be addressed. However, when it is necessary to rehome dogs, this should ideally take place in the country and national region of origin. When geographically distant relocation occurs, veterinary professionals have a vital role to play in public education, vigilance for detection of exotic vectors and infections, and alerting the medical community to the risk(s) for pathogen spread. With appropriate veterinary intervention, dog welfare needs can be met without inadvertently allowing global spread of parasites and their vectors.
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http://dx.doi.org/10.1186/s13071-020-04407-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7653694PMC
November 2020

Canine Toxocariosis: Its prevalence, incidence and occurrence in the Indian subcontinent.

Adv Parasitol 2020 10;109:819-842. Epub 2020 Feb 10.

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States.

Toxocariosis is an important neglected tropical helminth disease of zoonotic significance for which canids are the definitive hosts. Dogs are also considered the sentinel host for the occurrence of T. canis infections in humans. Therefore, understanding its prevalence in canine population is imperative for any effective disease control in humans. A comprehensive review of literature on the prevalence of T. canis in canids was lacking from the Indian subcontinent which necessitated our efforts to compile available data published on this topic. Data on prevalence, incidence and occurrence of this helminths in canids were presented in this review as tabular format for easy comprehension. Moreover, the data were categorized based on the region where the studies were conducted with an aim to understand the spatial distribution of this parasite in the subcontinent. Factors influencing the regional prevalence/occurrence of T. canis such as type of canids (stray or pet), age, sex, breed, season and the choice of analytical methods were also discussed. In addition, data on the prevalence of T. canis in environmental samples and in zoo canids were also compiled and presented. We anticipate such an exhaustive review of literature available mostly in the journals published from the subcontinent would become a point source of information necessary for prioritizing future surveillance efforts in this region and for making informed policy decision to control this zoonotic helminth infection.
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http://dx.doi.org/10.1016/bs.apar.2020.01.018DOI Listing
May 2021

Visceral larval migrans of Toxocara canis and Toxocara cati in non-canid and non-felid hosts.

Adv Parasitol 2020 1;109:63-88. Epub 2020 Apr 1.

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States. Electronic address:

Toxocara canis and Toxocara cati are considered the most ubiquitous gastrointestinal helminths in domesticated canids and felids. Ascarid eggs passed in the faeces of canids and felids in a suitable environment may remain infective for years and are capable of infecting not only canids and felids, but a large range of other vertebrate paratenic hosts, including man. Infection with Toxocara species also occurs following the ingestion of paratenic hosts containing infective larvae. As infective larvae are incapable of completing their lifecycle in these hosts, they instead travel to different parts of the body, sometimes inducing inflammatory responses, and in some cases remaining entrapped in the body for years. Migration routes depend on the host species; however, nearly all organs may be affected with varying quantities of larval burdens.
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http://dx.doi.org/10.1016/bs.apar.2020.02.001DOI Listing
May 2021

The anatomy of the third-stage larva of Toxocara canis and Toxocara cati.

Authors:
Dwight D Bowman

Adv Parasitol 2020 21;109:39-61. Epub 2020 Apr 21.

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States. Electronic address:

This review describes the morphology and ultrastructure of the third-stage larva of Toxocara canis, the larval stage that hatches from the egg and persists in the tissues of various paratenic hosts including infected humans. This larva remains unchanged as it passes from host to host and lives for extended periods in this same body form until it makes its way to the gastro-intestinal tract of its final host. There has been less work on the anatomy and ultrastructure of the larva of Toxocara cati, but overall, it appears very similar to that of T. canis with the only apparent difference being that the larva is a few microns thinner in diameter. The paper describes the anatomy and ultrastructure of the larva and the various major structures of the various body systems including the cuticle, hypodermis, the nervous tissue, oesophagus and the lumen-free intestine, and the large excretory gland cell that fills much of the pseudocoel and which appears to be the source of the components that are recognized immunologically by the infected host. It is suggested that further detailed studies on the larva could provide significant information that would allow a greater understanding of how the larva persists within these hosts and may provide information that would make the larva an excellent link to work on nematode anatomy that would link the work being done with this model system to that of Caenorhabditis elegans and the large amount of historical work already performed on adult ascaridoid nematodes.
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http://dx.doi.org/10.1016/bs.apar.2020.03.002DOI Listing
May 2021

History of Toxocara and the associated larva migrans.

Authors:
Dwight D Bowman

Adv Parasitol 2020 3;109:17-38. Epub 2020 Apr 3.

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States. Electronic address:

This review covers the systematics and nomenclature of the Ascaridoid genus toxocara, and more specifically the species Toxocara canis and Toxocara cati. Also discussed is the discovery of the persistence of these larvae in the tissues of paratenic hosts, and the role that other species of this genus might or could play in other such hosts; including those where the life cycle has been described, i.e., Toxocara vitulorum, Toxocara pteropodis, Toxocara mackerrasae, and Toxocara tanuki. Also examined is the work that led to the realization that the larval stage leaving the egg actually being a third rather than a second stage larva. Also discussed on the work showing that the larvae can persist in paratenic host with remarkable longevity without undergoing any morphological change for years and that these larvae can be transmitted from one paratenic host to another by ingestion. People are usually infected by the ingestion of eggs containing third-stage larvae, but infections also occur on occasions from the ingestion of uncooked paratenic hosts.
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http://dx.doi.org/10.1016/bs.apar.2020.01.037DOI Listing
May 2021

Canine vector-borne disease in domestic dogs on Isla Santa Cruz, Galápagos.

Vet Parasitol Reg Stud Reports 2020 01 17;19:100373. Epub 2020 Jan 17.

Cornell University, College of Veterinary Medicine, 602 Tower Road, Ithaca, NY 14850, United States of America.

Vector-borne diseases result in significant morbidity and mortality in domestic dogs in tropical and subtropical regions and also pose a potential threat to wildlife species and humans. Ehrlichia canis, the causative agent of canine monocytic ehrlichiosis (CME), has a high reported seroprevalence in dogs on Santa Cruz in the Galápagos Islands, Ecuador. Veterinary diagnostic and treatment resources are often scarce and clinical follow-up is lacking in the Galápagos. This study evaluated 58 dogs presenting to the Darwin Animal Doctors clinic in the city of Puerto Ayora on Santa Cruz Island during August of 2018. The seroprevalence of E. canis/Ehrlichia ewingii (48.3%), Anaplasma phagocytophilum/Anaplasma platys (12.1%), and Borrelia burgdorferi (0%), as well as the proportion of dogs actively infected with E. canis (12.1%) and E. ewingii (0%), are reported. Active infection was defined as the identification of antigen by PCR. Dogs with a packed cell volume (PCV) ≤ 30% had a 10-fold risk of active infection with E. canis compared to dogs with a PCV ≥ 31% (p = .0124). A PCV cutoff of 30% may be a useful screening tool for active E. canis infection in regions with high Ehrlichia seroprevalence, in the absence of other apparent causes of anemia. Dirofilaria immitis antigen was present in 6.9% of examined dogs, with the highest prevalence in the barrio Las Ninfas. PCR and Sanger sequencing were used to provide the first molecular identification of D. immitis in the Galápagos. This study updates the seropositivity and prevalence data of these canine vector-borne pathogens and highlights the need for continued surveillance in the region.
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http://dx.doi.org/10.1016/j.vprsr.2020.100373DOI Listing
January 2020

Canine vector-borne disease: mapping and the accuracy of forecasting using big data from the veterinary community.

Anim Health Res Rev 2019 06 26;20(1):47-60. Epub 2019 Sep 26.

School of Mathematical and Statistical Sciences, Clemson University, Clemson, SC, USA.

Diagnosis, treatment, and prevention of vector-borne disease (VBD) in pets is one cornerstone of companion animal practices. Veterinarians are facing new challenges associated with the emergence, reemergence, and rising incidence of VBD, including heartworm disease, Lyme disease, anaplasmosis, and ehrlichiosis. Increases in the observed prevalence of these diseases have been attributed to a multitude of factors, including diagnostic tests with improved sensitivity, expanded annual testing practices, climatologic and ecological changes enhancing vector survival and expansion, emergence or recognition of novel pathogens, and increased movement of pets as travel companions. Veterinarians have the additional responsibility of providing information about zoonotic pathogen transmission from pets, especially to vulnerable human populations: the immunocompromised, children, and the elderly. Hindering efforts to protect pets and people is the dynamic and ever-changing nature of VBD prevalence and distribution. To address this deficit in understanding, the Companion Animal Parasite Council (CAPC) began efforts to annually forecast VBD prevalence in 2011. These forecasts provide veterinarians and pet owners with expected disease prevalence in advance of potential changes. This review summarizes the fidelity of VBD forecasts and illustrates the practical use of CAPC pathogen prevalence maps and forecast data in the practice of veterinary medicine and client education.
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http://dx.doi.org/10.1017/S1466252319000045DOI Listing
June 2019

Canine Leishmaniasis Control in the Context of One Health.

Emerg Infect Dis 2019 12;25(12):1-4

Dogs are the main reservoir of Leishmania infantum and in some countries have been regularly culled as part of government policy to control visceral leishmaniasis. At the 13th Symposium of the Companion Vector-Borne Diseases World Forum in Windsor, UK, March 19-22, 2018, we consolidated a consensus statement regarding the usefulness of dog culling as a means of controlling visceral leishmaniasis. The statement highlighted the futility of culling infected dogs, whether healthy or sick, as a measure to control the domestic reservoir of L. infantum and reduce the risk for visceral leishmaniasis.
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http://dx.doi.org/10.3201/eid2512.190164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874277PMC
December 2019

Current time-temperature relationships for thermal inactivation of eggs at mesophilic temperatures are too conservative and may hamper development of simple, but effective sanitation.

Water Res X 2019 Dec 3;5:100036. Epub 2019 Sep 3.

Center for Applied Geosciences, University of Tübingen, 72074, Tübingen, Germany.

eggs are commonly used as indicators for pathogen inactivation during the treatment of fecal sludge and wastewater due to their highly resistant lipid membrane and ability to survive in the environment for long periods of time. Current guidelines suggest that thermal treatment alone cannot inactivate eggs at temperatures below 45 °C, although some evidence in the literature suggests this to be incorrect. Here, we performed a controlled experiment to test the effect of mesophilic temperatures on inactivation. We exposed eggs to a temperature gradient between 34°C and 45 °C under anaerobic and aerobic conditions to observe the required exposure times for a 3-log reduction. Indeed, we found that temperatures lower than 45 °C did inactivate these eggs, and the required exposure times were up to two orders of magnitude shorter than suggested by current guidelines. Results from the anaerobic exposures were used to develop a time-temperature relationship that is appropriate for inactivation at mesophilic temperatures. Data from the literature demonstrated that our relationship is conservative, with faster inactivation occurring under environmental conditions when eggs were suspended in fecal sludge or manure. A specific aerobic relationship was not developed, but we demonstrated that aerobic conditions cause faster inactivation than anaerobic conditions. Therefore, the anaerobic relationship provides a conservative guideline for both conditions. We demonstrate that relatively low temperatures can considerably impact viability and suggest that mesophilic temperatures can be used in waste treatment processes to inactivate pathogens. The development of safe, low-input, mesophilic treatment processes is particularly valuable for ensuring universal access to safe sanitation and excreta management.
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http://dx.doi.org/10.1016/j.wroa.2019.100036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6743028PMC
December 2019

Distribution of the feline lungworm in the USA based on fecal testing.

JFMS Open Rep 2019 Jul-Dec;5(2):2055116919869053. Epub 2019 Sep 3.

College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.

Objectives: The aim of this study was to compile commercial reference laboratory data over a 10-year period to determine the distribution of , commonly known as feline lungworm, within the USA based on widespread fecal testing in cats.

Methods: The results of 3,610,455 feline ova and parasite (O&P) zinc sulfate centrifugation fecal flotation tests performed at IDEXX Reference Laboratories in the USA from January 2008 to December 2017 were compiled and sorted for tests positive for larvae. The results of 3625 Baermann tests, currently considered the gold standard diagnostic for feline lungworm, were also retrieved from the same period.

Results: Of the tests performed, 4721 (0.13%) feline O&P zinc sulfate centrifugation fecal flotation tests and 75 (2.07%) of the Baermann tests conducted were positive for the presence of larvae. The O&P data revealed a significant association between infection status and sex, while male cats in both the O&P and Baermann data sets had a higher risk of infection than females. Significant variation in positive rates were observed by region and most positive cases were clustered in the Northeast, Midwest and West regions of the USA.

Conclusions And Relevance: This study highlights the distribution of feline lungworm in the USA and the limitations of using current testing to diagnose this infection. The introduction of higher throughput, less labor-intensive diagnostic methods could help increase awareness of this parasite among veterinary professionals, achieve a greater understanding of epidemiological factors, and improve the care and treatment for clinically ill feline patients.
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http://dx.doi.org/10.1177/2055116919869053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6727092PMC
September 2019

ProHeart® 12, a moxidectin extended-release injectable formulation for prevention of heartworm (Dirofilaria immitis) disease in dogs in the USA for 12 months.

Parasit Vectors 2019 Jul 26;12(1):369. Epub 2019 Jul 26.

Cornell University, Ithaca, NY, USA.

Background: The efficacy of an extended-release injectable moxidectin (0.5 mg/kg) suspension (ProHeart® 12) (PH 12) in preventing the development of Dirofilaria immitis in dogs for 12 months was investigated in laboratory and field studies in the USA.

Methods: In each of two laboratory studies, 20 dogs ≥ 12 months of age were randomly allocated to receive a subcutaneous injection of saline or PH 12 on Day 0 and were then inoculated with 50 D. immitis third-stage larvae (L) on Day 365. All dogs were necropsied ~ 5 months post-inoculation for adult worm counts. The field efficacy study included dogs ≥ 10 months of age from 19 veterinary clinics in the USA treated with either 20 monthly doses of Heartgard® Plus (HG Plus) (296 dogs) or two doses of PH 12 (297 dogs) on Days 0 and 365. Efficacy was determined on Days 365, 480 and 605 using adult HW antigen and microfilaria testing to assess adult HW infection.

Results: PH 12 was 100% effective in preventing HW disease in all three of these studies. In the laboratory studies, no PH 12-treated dogs had any adult HWs, whereas all control dogs in both studies had adult HWs [geometric mean, 30.2 (range, 22-37) for Study 1 and 32.6 (22-44) for Study 2]. In the field study, all dogs treated with PH 12 tested negative for adult HW infection on all test days (Days, 365, 480 and 605), whereas four dogs receiving HG Plus (positive control) tested positive for HWs during the study (three dogs on Day 365 and one dog on Day 480). All four dogs treated with HG Plus that subsequently tested positive for HWs during the field study were from the lower Mississippi River Valley region, where HW resistance to macrocyclic lactone preventives has been confirmed to occur. PH 12 was significantly better than HG Plus in preventing heartworm disease in the field study (P = 0.0367). PH 12 was well-tolerated in both laboratory and field studies.

Conclusions: A single dose of ProHeart® 12 was 100% effective in preventing heartworm disease in dogs for a full year in both laboratory and field studies.
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http://dx.doi.org/10.1186/s13071-019-3632-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6660952PMC
July 2019

Isolation, genotyping and subtyping of single Cryptosporidium oocysts from calves with special reference to zoonotic significance.

Vet Parasitol 2019 Jul 22;271:80-86. Epub 2019 Jun 22.

College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.

The ability of the small-subunit ribosomal RNA (SSU rRNA) based nested PCR and Restriction Fragment Length Polymorphism (PCR-RFLP) to identify and genotype a single Cryptosporidium oocyst isolated from bovine faecal samples was evaluated in this study. In addition, subtyping was carried out by sequencing the 60 kDa glycoprotein (gp60) gene from the same single oocyst. Faecal samples were collected from 40 pre-weaned calves (5-20 days old) from 7 dairy farms located in 3 different counties within the Finger Lakes region of Upstate New York. All the samples were microscopically positive for Cryptosporidium spp. A total of 400 Cryptosporidium oocysts (10 single oocysts from each calf sample) were individually isolated and analyzed using a nested PCR targeting the SSU rRNA gene. The SSU rRNA gene was amplified in 324 (81%) individual oocysts. All SSU rRNA amplified individual oocysts DNA was genotyped using PCR-RFLP. C. parvum was the only identified species; 107 single oocysts generated PCR products from the A gene, 18 generated PCR products from the B gene and 199 generated PCR products from both. Sequence analysis of the gp60 gene in 99 individual oocysts revealed the presence of only subtype IIaA15G2R1 with 99.4-100% and 99.1-100% identity of nucleotides and amino acids, respectively. These sequences were identical (100%) in oocysts from 35 calves and exhibited mutations in the non-repeat region of the gp60 gene in those of 5 other calves. The examination of DNA from individual oocysts with genotyping and subtyping tools provides methodology to more clearly define the genetic characteristics of Cryptosporidium spp. on farms and within individual animals.
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http://dx.doi.org/10.1016/j.vetpar.2019.05.003DOI Listing
July 2019

Coproantigen Detection Augments Diagnosis of Common Nematode Infections in Dogs.

Top Companion Anim Med 2019 Jun 6;35:42-46. Epub 2019 Apr 6.

IDEXX Laboratories Inc, Westbrook, ME 04092, USA; Pine Point Veterinary Hospital, Scarborough, ME 04074, USA.

Microscopic methods which employ active or passive flotation have been used to detect parasite diagnostic stages in the feces of companion animals for many years. More recently, coproantigen ELISAs for the detection of excretory/secretory products from intestinal nematodes have been introduced. These assays can identify the presence of parasites when eggs are not recovered by flotation (e.g. prepatent infection or intermittent egg shedding). The study was designed to assess the added benefit of these coproantigen tests in canine fecal diagnostics. The work was performed at 3 separate sites where canine fecal samples were each independently evaluated by both centrifugal flotation with an expert examiner (CFE) and passive flotation with a less experienced examiner. All samples were also tested using coproantigen ELISA to detect ascarid, hookworm, or whipworm antigen (IDEXX Laboratories, Inc, Westbrook, Maine). A total of 1202 samples were collected; 626 were from shelter dogs and 576 were from pet dogs. CFE recovered ascarid eggs in 58 samples, hookworm eggs in 229 samples, and whipworm eggs in 95 samples. Of the positive samples identified by CFE, the PFE and ELISA identified 40 and 51 ascarid samples, 188 and 203 hookworm samples, and 65 and 67 whipworm positive samples, respectively. The coproantigen ELISA identified 8 ascarid, 82 hookworm, and 22 whipworm positive samples that were not detected by CFE. The combined results of passive flotation and the coproantigen ELISA improved the percent agreement with centrifugal flotation, suggesting that greater sensitivity of detection may be achieved through the use of complementary diagnostic methods. However, errors of misidentification and poor recovery apparently introduced by less experienced examiners using an inferior flotation method remained. A diagnostic approach that combines coproantigen assays with centrifugal flotation and examination by an expert allows detection of more ascarid, hookworm, and whipworm infections.
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http://dx.doi.org/10.1053/j.tcam.2019.04.001DOI Listing
June 2019

Culling Dogs for Zoonotic Visceral Leishmaniasis Control: The Wind of Change.

Trends Parasitol 2019 02 13;35(2):97-101. Epub 2018 Dec 13.

Department of Veterinary Medicine, Università degli Studi di Bari, Bari, Italy. Electronic address:

Visceral leishmaniasis, caused by Leishmania infantum, is a zoonosis, and culling seropositive dogs has been recommended to control the disease in some endemic countries. However, no scientific evidence supports the effectiveness of this strategy to reduce the incidence of visceral leishmaniasis. Economic and ethical issues concerning dog culling are discussed.
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http://dx.doi.org/10.1016/j.pt.2018.11.005DOI Listing
February 2019

Efficacy and safety of a new topical formulation of selamectin plus sarolaner in the treatment and control of natural infections of Ancylostoma tubaeforme and Toxocara cati in cats presented as veterinary patients in the United States.

Vet Parasitol 2019 Jun 11;270 Suppl 1:S45-S51. Epub 2018 Nov 11.

Zoetis, Veterinary Medicine Research and Development, 333 Portage Street, Kalamazoo, MI, 49007, USA.

A new topical formulation of selamectin plus sarolaner (Revolution Plus/Stronghold Plus, Zoetis) was evaluated in the treatment and control of naturally occurring infections of Ancylostoma tubaeforme and Toxocara cati in cats presented as veterinary patients in the United States. Three thousand three hundred three (3303) cats were screened in 25 veterinary practices in 15 states and 153 hookworm-positive cats (A. tubaeforme and/or A. braziliense), mainly from Alabama, Mississippi, Texas, and Hawaii, were identified; 135 cats met all the criteria for enrollment and were included on study. The cats were randomly assigned to treatment with Revolution (at the label dosage, to provide a minimum dosage of 6 mg/kg selamectin) or selamectin plus sarolaner (at a dosage of 6-12 mg/kg plus 1-2 mg/kg, respectively). Treatments were administered at the time of enrollment and repeated 30 days later. Fecal samples were collected for differential fecal egg count prior to the first treatment (Day 0), prior to the second treatment (Day 30), and approximately 30 days later (Day 60). Efficacy was based on the percentage reductions in geometric mean fecal egg count for A. tubaeforme on Day 30 and Day 60 compared with Day 0. Where cats were co-infected with T. cati, efficacy against this species was also evaluated. Efficacy data were evaluated for A. tubaeforme for 40 cats on both Day 30 and Day 60 for the group treated with the selamectin/sarolaner combination and reductions in geometric mean fecal egg counts of 99.4% and 99.7% were demonstrated for Day 30 and Day 60, respectively. For the group treated with selamectin alone, 44 and 40 cats were evaluated and percent reductions for Day 30 and Day 60 were 99.5% and 99.9%, respectively. For T. cati, 14 cats were evaluated in the selamectin/sarolaner-treated group for Day 30 and for Day 60, and the reduction in geometric mean fecal egg count was 100% for both days. There were 11 and 9 cats evaluated for Day 30 and Day 60, respectively, for the selamectin-treated group and the reduction was again 100% for both days. The geometric mean fecal egg counts post-treatment were significantly lower than pre-treatment for both A. tubaeforme and T. cati, for both treatments, and for both periods of interest (P < 0.0001). No serious adverse events related to treatment with either product occurred during the study. Thus, both selamectin alone and the combination product of selamectin/sarolaner were safe and effective when administered on a monthly basis for the treatment and control of natural infections of A. tubaeforme and T. cati. The addition of sarolaner to the formulation did not interfere with the efficacy of selamectin against these nematodes.
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http://dx.doi.org/10.1016/j.vetpar.2018.10.012DOI Listing
June 2019

Comparative performance of reference laboratory tests and in-clinic tests for Giardia in canine feces.

Parasit Vectors 2018 Aug 1;11(1):444. Epub 2018 Aug 1.

College of Veterinary Medicine, Cornell University, C4-114 VMC, 930 Campus Rd, Ithaca, NY, 14853, USA.

Background: We examined the performance of four in-clinic Giardia diagnostic tests by comparing results to three laboratory methods for detection of Giardia. A set of 177 fecal samples originally submitted to a commercial laboratory by veterinarians for routine ova and parasite (O&P) testing was used. Specimens were examined by direct immunofluorescence assay (DFA) for presence of Giardia cysts which served as the gold standard. Fecal samples were tested using a Giardia-specific cyst wall antigen microtiter plate format enzyme-linked immunosorbent assay (ELISA) and each of the in-clinic assays adhering to the package insert for each kit.

Results: Evaluated were four in-clinic antigen test kits: VetScan® Canine Giardia Rapid Test (Abaxis), Anigen® Rapid CPV-CCV-Giardia Antigen Test (BioNote), SNAP® Giardia Test (IDEXX) and Witness® Giardia Test (Zoetis). In the comparison of the in-clinic tests to the DFA standard test sensitivity ranged between 70.0-87.1%, and specificity ranged between 71.1-93.4%.

Conclusion: Of the tests evaluated here, the SNAP test had the highest sensitivity and specificity. The SNAP test had the highest percent positive and percent negative agreement when compared to the microtiter plate format ELISA and the O&P assay.
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http://dx.doi.org/10.1186/s13071-018-2990-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6090814PMC
August 2018

Bacillus thuringiensis Cry5B protein as a new pan-hookworm cure.

Int J Parasitol Drugs Drug Resist 2018 08 4;8(2):287-294. Epub 2018 May 4.

Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA. Electronic address:

Hookworms are intestinal nematode parasites that infect nearly half a billion people and are globally one of the most important contributors to iron-deficiency anemia. These parasites have significant impacts in developing children, pregnant women and working adults. Of all the soil-transmitted helminths or nematodes (STNs), hookworms are by far the most important, with disease burdens conservatively estimated at four million DALYs (Disability-Adjusted Life Years) and with productivity losses of up to US$139 billion annually. To date, mainly one drug, albendazole is used for hookworm therapy in mass drug administration, which has on average ∼80% cure rate that is lower (<40%) in some places. Given the massive numbers of people needing treatment, the threat of parasite resistance, and the inadequacy of current treatments, new and better cures against hookworms are urgently needed. Cry5B, a pore-forming protein produced by the soil bacterium Bacillus thuringiensis (Bt) has demonstrated good efficacy against Ancylostoma ceylanicum hookworm infections in hamsters. Here we broaden studies of Cry5B to include tests against infections of Ancylostoma caninum hookworms in dogs and against infections of the dominant human hookworm, Necator americanus, in hamsters. We show that Cry5B is highly effective against all hookworm parasites tested in all models. Neutralization of stomach acid improves Cry5B efficacy, which will aid in practical application of Cry5B significantly. Importantly, we also demonstrate that the anti-nematode therapeutic efficacy of Cry5B is independent of the host immune system and is not itself negated by repeated dosing. This study indicates that Bt Cry5B is a pan-hookworm anthelmintic with excellent properties for use in humans and other animals.
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http://dx.doi.org/10.1016/j.ijpddr.2018.05.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039361PMC
August 2018

Unsticking from time to create a parasitologic amalgamation.

Authors:
Dwight D Bowman

Vet Parasitol 2018 Mar 31;252:98-100. Epub 2018 Jan 31.

Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA. Electronic address:

Parasitology is a relevant and integral part of veterinary medicine, and the WAAVP membership has skills ranging from morphological diagnostics and routine parasite control recommendations through the cutting edges of many disciplines, e.g., pharmacology, immunology, molecular biology and genomics. We regularly face a majority of students who want only the practical information useful the moment they enter the clinics. However, we are preparing them for careers lasting 30-50 years. Thus, we also must help them prepare for their futures. There is a constant squeeze on parasitology in the curricular footprint accompanying a mandatory need to cover the licensure basics. The basic material has stood the test of time, and until the agents are eradicated or the hosts extinct, they have value. But, a critical need is the interweaving of the marvels of modern science into the parasitology regularly presented. Often this has been done with boxes, highlights, or examples within classes or texts, but asides are mentally treated as such. Also, many of those teaching parasitology are unfamiliar with many of the concepts and details of this material, but these same folks remain a grand part of the profession. Also, it is hard to sneak this apparently unwarranted material past the clinically oriented veterinary student. Somehow, WAAVP needs to work with its membership to develop and assist faculty in the presentation of a curriculum that can meld the old and the avant guard into a fusion of tastes and flavours palatable to today's veterinary student and tomorrow's practitioner.
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http://dx.doi.org/10.1016/j.vetpar.2018.01.027DOI Listing
March 2018

Examination of the "susceptibility gap" in the treatment of canine heartworm infection.

Parasit Vectors 2017 Nov 9;10(Suppl 2):513. Epub 2017 Nov 9.

ELANCO, Greenfield, IN, USA.

Background: The "susceptibility gap" in a dog diagnosed with adult heartworms has been defined as the period of time in which some Dirofilaria immitis stages are not susceptible to treatment with either macrocyclic lactones or melarsomine dihydrochloride. This was previously defined within the American Heartworm Society guidelines as a period of about 3 months "as per product labels." It can be postulated, however, that a susceptibility gap does not exist with the combination of continued macrocyclic lactone therapy coupled with a three-dose melarsomine dihydrochloride protocol where the first intramuscular treatment is near the time of first diagnosis.

Discussion: Melarsomine dihydrochloride was originally also investigated as a "preventive" as well as a treatment for adult heartworm infection where it would be given to dogs by intramuscular injection every 4 months; therefore, there was early interest in its ability to kill younger worms. A single intramuscular injection of 2.5 mg melarsomine dihydrochloride/kg has an efficacy of 82.1% against 4-month-old worms. When it was given to dogs with older heartworms, 7 and 12 months of age, a single injection was only 55.6% and 51.7% effective, respectively. Thiacetarsamide has been shown to be 99.7% effective against 2-month-old heartworms and other work has shown that melarsomine dihydrochloride is 100% efficacious against these younger forms. With the development and US Food and Drug Administration (FDA) approval of spinosad + milbemycin oxime (Trifexis®, Elanco), milbemycin oxime + praziquantel (Interceptor® Plus, Novartis, now Elanco), and milbemycin oxime + lufenuron + praziquantel (Sentinel® Spectrum®, Novartis, now Virbac), it was shown that repeated treatments of dogs with milbemycin oxime also has efficacy against 3-month-old heartworms. Thus, no improvement in efficacy is expected with a delay in initiating therapy with both melarsomine dihydrochloride and macrocyclic lactones, even with the presence of younger heartworms. Starting treatment at diagnosis appears to be acceptable for maximal heartworm clearance based on published data. Delaying treatment has the disadvantage of allowing disease progression and continued heartworm growth.

Conclusions: The collective data that has been reviewed indicates that continued macrocyclic lactone administration with two additional injections of melarsomine dihydrochloride a month later will protect dogs against all heartworm stages, including those heartworms 2 months of age or younger at diagnosis, when both treatments are started upon diagnosis.
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http://dx.doi.org/10.1186/s13071-017-2433-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5688481PMC
November 2017

Efficacy of 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi for Dogs) for the prevention of heartworm disease and infection all month long.

Parasit Vectors 2017 Nov 9;10(Suppl 2):478. Epub 2017 Nov 9.

Bayer Animal Health, Shawnee, KS, USA.

Background: Prior work has shown that the levels of moxidectin in dogs treated with Advantage Multi® for Dogs (Bayer Animal Health) remain at a high plasma concentration for the full month after application. The objective of this study was to demonstrate the efficacy of 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs, also known as Advocate® for Dogs) for the prevention of heartworm infection and disease 30 days after just one application.

Methods: Two groups of eight dogs each were included. Dogs in Group 1 received the product (Advantage Multi® for Dogs) while those in Group 2 remained as nontreated controls. All dogs entering the study completed a physical examination including examination for Dirofilaria immitis antigen and circulating microfilariae. Dogs in Group 1 were treated on Study Day (SD) -30 as per the label recommendation. Thirty days later (SD 0) dogs in Groups 1 and 2 were subcutaneously infected in the inguinal region with approximately 50 infective third-stage D. immitis larvae ("Missouri" isolate). Blood was collected on SDs 120 and 147 for examination for D. immitis antigen and circulating microfilariae. On SD 148, all animals were euthanized and necropsied for recovery of adult heartworms. All procedures were performed in accordance with the VICH GL9 guidelines.

Results: Examination and worm counts made at necropsy showed no heartworms in the treated dogs (Group 1) compared with six of eight nontreated dogs (Group 2) with heartworms (range of 2-33). The treated dogs (Group 1) had significantly fewer heartworms (p < 0.05) compared with the nontreated controls (Group 2).

Conclusion: The results demonstrated that 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs) is efficacious for the prevention of heartworm infection and disease all month long with no observation of treatment-related adverse events.
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http://dx.doi.org/10.1186/s13071-017-2432-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5688421PMC
November 2017

Evaluation of the efficacy of ProHeart 6 (moxidectin) against a resistant isolate of Dirofilaria immitis (JYD-34) in dogs.

Parasit Vectors 2017 Nov 9;10(Suppl 2):502. Epub 2017 Nov 9.

Zoetis, Kalamazoo, MI, USA.

Background: In a previous study, it was demonstrated that ProHeart 6 (PH6) (moxidectin, Zoetis) provided only about 20% efficacy in a small six-dog study against a macrocyclic lactone -resistant Dirofilaria immitis isolate (Jd2009-2) when dogs were inoculated with infective third-stage larvae (L3) at the end of the dosing period (ie, 180 days post treatment). The objective of the current study was to determine the prophylactic efficacy of a moxidectin sustained-release formulation (PH6) against a confirmed macrocyclic lactone-resistant isolate of D. immitis (JYD-34) in dogs when administered by subcutaneous injection at the labeled dose of 0.17 mg/kg 2 days before L3 inoculation. This was intended to model the scenario where dogs become infected with resistant heartworms at the end of the PH6 treatment period (ie, 6 months post treatment) when dogs would routinely be given another injection under normal field use.

Methods: Twelve purpose-bred Beagle dogs (six males and six females) were selected and randomly allocated to two groups, untreated controls and PH6-treated dogs in groups of six each. The dogs were ≥8 months old at the start of the study, and using blood samples collected on Day -7 were shown to be negative for adult heartworm antigen and microfilariae. On Day 0, the dogs in the untreated control group were administered saline subcutaneously by injection, and the dogs in the treated group were administered PH6 according to label instructions. On Day 2, each dog was inoculated in the inguinal area with 50 L3 of D. immitis. The dogs were necropsied on Day 150 (148 days post infection), and the worms were collected and counted.

Results: All of the six control dogs were infected and harbored a range of 21 to 37 worms (geometric mean, 25.4; 10.9 males and 13.9 females). Only one of the six PH6 dogs was found to be infected, harboring a single male worm. Efficacy was 99.5% (geometric mean).

Conclusion: ProHeart 6 was highly effective in preventing the development of heartworms in dogs challenged with a confirmed macrocyclic lactone-resistant heartworm isolate (JYD-34) 2 days prior to treatment.
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http://dx.doi.org/10.1186/s13071-017-2431-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5688425PMC
November 2017
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